N.H. Rev. Stat. Ann. § 227-L:25

The governor on behalf of this state is hereby authorized to enter into a compact, substantially in the following form, with any one or more of the states of Connecticut, Maine, New York, Rhode Island, and Vermont, and the Commonwealth of Massachusetts, and with such other states of the United States or provinces of the Dominion of Canada as may legally join therein, and the legislature hereby signifies in advance its approval and ratification of such compact so entered into, such approval and ratification to be effective upon the filing of a copy of such compact in the office of the secretary of state.